CN105444872A - Vibration sensor based on nanoparticle lattice quantum transport characteristic - Google Patents

Abstract

The invention provides a vibration sensor based on a nanoparticle lattice quantum transport characteristic. The vibration sensor comprises a metal nanoparticle lattice (1), a cantilever beam (2) with microelectrodes (3), a base (4) and a mass block (5), wherein the metal nanoparticle lattice (1) is prepared at the surface of the cantilever beam (2) and is disposed between the pair of microelectrodes (3); the cantilever beam (2) is long-strip-shaped, one end of the cantilever beam is fixed on the base (4), and the other end is a free end; the mass block (5) is attached to the free end of the cantilever beam (2); the metal nanoparticle lattice (1) is taken as a sensitive material of the sensor; and the metal nanoparticle lattice (1) is composed of various metal materials, the particle size of a nanoparticle is 1 to 500nm, and the coverage rate of the nanoparticle is 0.3 to 0.99 of a single layer.

Description

A Vibration Sensor Based on Quantum Transport Properties of Nanoparticle Lattice

technical field

The invention relates to a vibration sensor, in particular to a vibration sensor based on the quantum transport characteristics of nanoparticle lattice.

Background technique

Vibration sensors are an important monitoring method in the engineering field, and are widely used in aspects such as material flaw detection, fault diagnosis of mechanical systems, noise elimination, safety precautions, industrial automation, and dynamic characteristic analysis of structural parts.

At present, the mainstream vibration sensors can be divided into photoelectric type, piezoelectric type, eddy current type, electrodynamic type, and resistive type according to the principle of electromechanical transformation. Among them, the photoelectric type is a sensor that uses laser technology for measurement. Its components are lasers, laser detection devices, and measurement circuits. Its own influence cannot be ignored, and it can only be used in occasions where the vibration intensity is relatively weak, which greatly limits its application. Piezoelectric vibration sensors use piezoelectric crystals to generate polarization voltages on the surface after deformation to characterize the strain or vibration capability of the load. Due to the limited lattice distortion capability, the range of vibration amplitudes measured is very small. The eddy current sensor is a relative non-contact sensor, but because it needs to generate a strong high-frequency current, and requires the measured object to have ferromagnetic properties, its anti-magnetic interference is weak, and its own circuit also needs to be magnetically shielded. The electric sensor uses the internal permanent magnet to cut the magnetic induction line by the coil fixed by the spring during the vibration process to generate an electromotive force output. Its anti-magnetic interference is weak, which is not conducive to miniaturization and modularization. The resistive sensor converts the measured mechanical vibration into the change in the resistance of the sensing element. Its structure is relatively simple, safe, and has a high tolerance to the environment. The invention is a resistive vibration sensor.

The present invention aims to provide a high-sensitivity vibration sensor based on nanotechnology and a method for measuring vibration. The sensor combines metal nanoparticle lattice with cantilever beam sensor to form a new resistive vibration sensing device. And it can be integrated into MEMS devices, which has the characteristics of small size, large measuring range and high sensitivity. Moreover, the technology provided by the present invention enables performance parameters such as the frequency response range, amplitude response sensitivity, and amplitude measurement range of the vibration sensor to be designed through the material, shape, and size of the cantilever beam of the sensor.

Contents of the invention

The purpose of the present invention is to propose a vibration sensor and a vibration measurement method based on the quantum transport characteristics of nanoparticle lattices. Another object of the present invention is to provide a method for measuring mechanical vibration using a nanoparticle lattice as a sensitive material.

In order to achieve the above object, the technical scheme of the present invention is, based on the vibration sensor of nanoparticle lattice quantum transport characteristics, including metal nanoparticle lattice (1), cantilever beam (2) with microelectrode (3), foundation ( 4) and mass (5); wherein, the nanoparticle lattice (1) is prepared on the surface of the cantilever beam (2) and is located between a pair of microelectrodes (3); the cantilever beam (2) is in the shape of a long strip, and one end is fixed On the foundation (4), the other end is a free end; a mass block (5) is attached to the free end of the cantilever beam (2); the metal nanoparticle lattice (1) is used as the sensitive material of the sensor; the nanoparticle lattice ( 1) The material can be various metals, the particle size of the nanoparticles is 1-500nm, and the coverage of the nanoparticles is between 0.3-0.99 monolayers. The microelectrodes (3) are made of metal thin film materials such as gold, silver, copper, and aluminum.

The cantilever beam (2) is made of elastic insulating material, and can also be made of non-insulator elastic material with a surface insulating layer.

No ohmic contact is formed between the nanoparticles in the nanoparticle lattice (1).

The nanoparticle lattice (1) and the microelectrode (3) prepared on the same cantilever beam can be connected in parallel in one group or in multiple groups.

The base (4) vibrates in contact with the vibration source. Driven by the inertia of the base mass (5), the cantilever beam (2) responds to the vibration of the vibration source and strains the surface, thereby making the nanoparticle lattice (1) The distance between the nanoparticles changes, and the change of the distance between the nanoparticles causes the conductance of the nanoparticle lattice (1) to change; the detection of the vibration is realized by measuring the change of the conductance (or resistance) between the micro-electrodes.

The frequency response parameters of the vibration sensor can be adjusted according to the mass of the mass (5), the mass (5) is not necessary, and the mass m (5) can also be removed under certain conditions.

The invention also provides a vibration sensor and a vibration measurement method based on the quantum transport characteristics of the nanoparticle lattice. Metal electrodes are prepared on the cantilever beam, and metal nanoparticles are deposited between the electrodes with a predetermined number density to form a metal nanoparticle lattice with a certain electrical conductivity. When the cantilever beam is deformed due to vibration, the conductance of the metal nanoparticle lattice will change synchronously, and the quantitative measurement of the vibration spectrum can be realized by monitoring the change of the conductance value through the electrodes. The vibration sensor based on metal nanoparticle lattice structure has the advantages of high sensitivity, reliable performance, easy integration, and low price, and the sensor amplitude and frequency response characteristics can be adjusted by changing the selection of cantilever beam material and shape parameters.

The principle of the sensor can be explained by the cantilever beam model, assuming that the length of the cantilever beam is L, the width is b, and the thickness is h, and the nanoparticle lattice is located on the side of the fixed end of the cantilever beam. When forced to vibrate, the vibration equation is assumed to be The disturbance generated by the free end of the cantilever beam is x _r = x, which causes the transverse strain of the nanoparticle lattice near the fixed end to be:

$\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ></span>$

From the knowledge of physics, it can be known that the change rate of the tunneling resistance of the nanoparticle lattice is:

$\frac{\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ></span>$

where _R0 is the initial resistance value of nanoparticles, β is a parameter related to the size and temperature of nanoparticles, and d is the average distance between nanoparticles. From the combination of <1> and <2>, we can get:

It can be known from formula <3> that the vibration information of the vibration source can be obtained by measuring the nanoparticle lattice resistance R(t).

With a relatively negligible cantilever beam weight, the resonant frequency of the sensor is:

${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; ></span>$

in is the stiffness of the cantilever beam, and E is the modulus of elasticity of the cantilever beam.

The closer the sensor's forced vibration frequency is to the resonance frequency, the stronger the measurement signal and the higher the measurement sensitivity. Therefore, the measurement performance of the sensor can be adjusted according to the material type, size and shape of the cantilever beam, and is also related to the mass m of the mass.

Based on the vibration sensor mentioned above, there are two methods for vibration measurement methods:

1. Fix the foundation so that it is in a static state, the vibration source drives the free end of the cantilever beam to vibrate, and at the same time measure the resistance or conductance of the nanoparticle lattice. As shown in Figure 6A.

2. The foundation and the vibration source are rigidly connected, the sensor as a whole vibrates with the vibration source, the cantilever beam vibrates back and forth under the inertia of the mass, and the resistance or conductance value of the nanoparticle lattice is measured at the same time. As shown in Figure 6B.

Beneficial effects: the vibration sensor based on the quantum transport characteristics of nanoparticle lattices provided by the present invention is composed of cantilever beams with microelectrodes and nanoparticle lattices distributed between the microelectrodes. The coverage of the nanoparticle lattice can be precisely controlled within 0.5-1 monolayer. The conductance of the nanoparticle lattice is measured by a microelectrode. Fix one end of the cantilever beam and leave the other end free. A mass with a certain mass can be attached to the free end of the cantilever beam. Under the action of the vibration source, the inertia of the mass and the cantilever beam itself causes the cantilever beam to vibrate synchronously with a large amplitude. According to the knowledge of material mechanics, when the cantilever beam is forced to vibrate, its surface will be strained, which will lead to changes in the distance between nanoparticles in the nanoparticle lattice, and then change the conductance value of the nanoparticle lattice. Vibration detection is achieved by measuring the change in conductance (or resistance) between microelectrodes.

Description of drawings

Fig. 1 is the front view of vibration sensor of the present invention;

Fig. 2 is a top view of the vibration sensor of the present invention;

Fig. 3 is the microelectrode design diagram described in the embodiment of the present invention;

Fig. 4 is the data graph that vibration sensor measures and obtains in the embodiment 1 of the present invention;

Fig. 5 is the data graph that vibration sensor measures and obtains in embodiment 2 of the present invention;

6A and 6B are respectively schematic diagrams of two vibration measurement methods of the vibration sensor in the present invention.

detailed description

Example 1

A ethylene terephthalate (PET) sheet is selected as the material of the cantilever beam, and the specific dimensions are: length L=50mm, width b=12mm, and thickness h=0.5mm. The interdigitated electrode is prepared at one end of PET by thermal evaporation masking method. The electrode material is metallic silver. The specific pattern and size ratio are shown in Figure 3. The height is about 4.5mm and the width is about 3mm. The base of the vibration sensor is made of aluminum alloy. Silver nanoparticles are deposited between the interdigitated electrodes by nanoparticle beam vapor deposition to form a nanoparticle lattice. The specific operation method of nanoparticle beam vapor deposition can be found in the literature Journal of Vacuum Science and Technology A12 (1994) 2925-2930. One end of the prepared PET substrate with nanoparticle lattice is fixed on the foundation to form a cantilever beam structure. Use a 50Hz vibration source (such as a dot timer) to drive the free end of the cantilever beam to perform simple harmonic vibration, and use a data acquisition card to monitor the change of the conductance between electrodes with vibration. Figure 4 is a diagram of the vibration signal measured by the vibration sensor.

Example 2

A ethylene terephthalate (PET) sheet is selected as the material of the cantilever beam, and the specific dimensions are: length L=50mm, width b=12mm, and thickness h=0.5mm. The interdigitated electrodes were prepared at one end of PET by thermal evaporation masking method. The electrode material was metallic silver. The specific pattern and size were shown in Figure 3. The vibration sensor was made of aluminum alloy material. A lead block with a mass of 50g is pasted on the end of the cantilever beam, and silver nanoparticles are deposited between the interdigital electrodes by nanoparticle beam vapor deposition to form a nanoparticle lattice. The specific operation method of nanoparticle beam vapor deposition can be See the literature Journal of Vacuum Science and Technology A12 (1994) 2925-2930. One end of the prepared PET substrate with nanoparticle lattice is fixed on the foundation to form a cantilever beam structure. Use a 30Hz vibration source (such as a dot timer) to drive the free end of the cantilever beam to perform simple harmonic vibration, and use a data acquisition card to monitor the change of the conductance between electrodes with vibration. Fig. 5 is a diagram of the vibration signal measured by the vibration sensor. Compared with embodiment 1, embodiment 2 adds mass m with a mass of 50 g. When a 30 Hz vibration source is used to drive the mass end to perform simple harmonic vibration, the vibration frequency is closer to its natural frequency than embodiment 1, and the vibration amplitude of the sensor is somewhat Larger, easier to measure. This also shows that the sensor involved in the present invention can optimize the measurement performance of the sensor by adjusting the mass of the mass m. , the cantilever beam is a thin plate, and the mass m is removed.

The present invention has been described above through two embodiments. Therefore, a person skilled in the present invention can realize it by various means within the scope of the appended claims without creative efforts.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (8)

1. A vibration sensor based on the quantum transport properties of nanoparticle lattices, characterized in that it comprises metal nanoparticle lattices (1), cantilever beams (2) with microelectrodes (3), foundations (4) and masses (5); wherein, the nanoparticle lattice (1) is prepared on the surface of the cantilever beam (2) and is located between a pair of microelectrodes (3); the cantilever beam (2) is in the shape of a strip, and one end is fixed to the foundation (4) The other end is a free end; a mass (5) is attached to the free end of the cantilever beam (2); the metal nanoparticle lattice (1) is used as the sensitive material of the sensor; the material forming the nanoparticle lattice (1) is Various metals, the particle size of the nanoparticles is 1-500nm, and the coverage of the nanoparticles is between 0.3-0.99 monolayers. 2. The vibration sensor based on nanoparticle lattice quantum transport properties as claimed in claim 1, characterized in that the microelectrodes (3) are made of gold, silver, copper or aluminum metal thin film materials. 3. the vibration sensor based on nanoparticle lattice quantum transport characteristics as claimed in claim 1, is characterized in that, cantilever beam (2) is made by the insulating material with elasticity, or is made of non-insulator elasticity with surface insulating layer. Material production. 4. The vibration sensor based on the quantum transport characteristics of the nanoparticle lattice according to claim 1, characterized in that no ohmic contact is formed between the nanoparticles in the nanoparticle lattice (1). 5. the vibration sensor based on nanoparticle lattice quantum transport characteristics as claimed in claim 1, is characterized in that, the nanoparticle lattice (1) and microelectrode (3) that are prepared on the same cantilever beam are one group or Parallel connection of multiple groups. 6. the vibration sensing method based on nanoparticle lattice quantum transport characteristics as claimed in claim 1, is characterized in that, foundation (4) contacts with vibration source and produces vibration, on the basis of the inertial drive of mass block (5) The lower cantilever beam (2) responds to the vibration of the vibration source and strains its surface, thereby causing the distance between nanoparticles in the nanoparticle lattice (1) to change, and the change in the distance between the nanoparticles causes the nanoparticle lattice (1) The conductance of the micro-electrode changes; the detection of vibration is realized by measuring the change of conductance or resistance between micro-electrodes. 7. the vibration sensor based on nanoparticle lattice quantum transport characteristics as claimed in claim 1, is characterized in that, the frequency response parameter of vibration sensor can be adjusted according to the quality of mass (5), or mass of mass is zero . 8. As one of claims 1-7, the vibration sensor based on the quantum transport characteristics of the nanoparticle lattice carries out the vibration measurement method, and it is characterized in that when the cantilever beam is deformed due to vibration, the conductance of the metal nanoparticle lattice will be synchronized Quantitative measurement of the vibration spectrum can be realized by monitoring the change of the conductance value through the electrode.